The present invention relates to an improved drilling machine including an annular cutter, which permits a more rapid conversion of centering to drilling.
With an annular cutter of the type designed and intended to form a bore of a diameter appreciably larger than that of a bore obtained by drilling, it is difficult, or even impossible, to precisely provide such a bore in a given position, since the center of the cutter is so unstable that it is not in axial alignment with the drilling machine. It has been found that this problem is solved by using an annular cutter of the type including a center drill. However, there is still left much to be desired as far as a rapid centering-to-drilling conversion is concerned.